Conventionally, card readers for reading magnetic data recorded in a card and recording magnetic data into a card are widely used. In the industry of financial organizations and the like in which card readers are used, traditionally so-called “skimming” is a serious issue in which a criminal installs a magnetic head at a card insertion part of a card reader so as to illegally obtain magnetic data of the card by use of the magnetic head. In order to avoid such a problem, proposed is a card reader equipped with a metal sensor for detecting a magnetic head for skimming (hereinafter, called a “skimming magnetic head”) having been installed at a front side of a card insertion part (for example, refer to Patent Document 1).
In a card reader described in Patent Document 1, a metal sensor is placed inside a card insertion part that is formed as a hollow part. Meanwhile, the metal sensor includes a core made of a magnetic material, a couple of exciting coils wound on the core, and a detection coil. In the case of this card reader; at a time when the metal sensor detects a foreign object including a metallic material, a predetermined process for handling an abnormal situation is executed, so that it becomes possible to prevent a skimming magnetic head, attached at a front side of the card insertion part, from reading magnetic data.